What is the complement system?
A) A set of 20 inactive proteins activated by the presence of a pathogen
B) Chemicals released by virally-infected cells that encourage the production of anti-viral protein
C) Chemicals that raise the body temperature
D) Chemicals released by damaged tissue to cause blood vessels to widen

Question

Quizplus · Accepted Answer

The complement system includes 20 inactive proteins (always present in the blood) that may be activated by the presence of a pathogen. Once activated, the proteins initiate one of several different pathways to ensure pathogen destruction through: increased inflammation, breaking apart of the pathogen (cytolysis), or coating a pathogenic cell to make it easier for a macrophage to phagocytize it (opsonization).

What Is the Complement System